生物炭对重金属钝化及抗性基因的影响

Studies on the effects of biochar application on variation of heavy metals and antibiotic resistance genes

探究了玉米秸秆生物炭(CB)和水稻壳生物炭(HB)对猪粪厌氧消化过程中重金属钝化和抗性基因削减的影响,并解析了影响抗生素抗性基因(ARGs)迁转的主要因素.研究发现,添加CB和HB后,促进了Cr,Cu,Pb和Zn转化为更稳定的金属形态,且投加HB有更优的重金属钝化效果.添加CB和HB均能降低ARGs的丰度,胞外抗性基因(eARGs)的去除率较高,约为55.6~98.3%,具有更大比表面积的HB能吸附更多eARGs.胞内抗性基因(iARGs)的变化受生物炭影响较小,iARGs的削减主要与宿主菌的去除相关.微生物群落结构(λ=0.83,P<0.01)和MGEs(λ=0.60,P<0.05)是影响ARGs改变的主要因素.添加生物炭没有直接影响ARGs迁转(λ=0.29,P>0.05),投加生物炭可减轻消化系统中的重金属选择性压力,从而间接促进ARGs的去除.

This study investigated the effects of corn straw biochar(CB)and rice husk biochar(HB)on heavy metal passivation efficiency and resistance genes reduction during anaerobic digestion(AD)of swine manure(SM).This study also investigated the main factors affecting the fate of antibiotic resistance genes(ARGs)during AD of SM.The addition of biochar CB and HB could promote the conversion of Cr,Cu,Pb,and Zn into more stable metal forms,and adding HB had a better heavy metal passivation effect.The addition of CB and HB reduced the absolute abundance of ARGs to varying degrees,and the removal efficiency of extracellular resistance genes(eARGs)was ranging from 55.6% to 98.3%.HB with a larger specific surface area could adsorb more extracellular resistance genes.The changes of intracellular resistance genes(iARGs)were less affected by biochar,and iARGs reduction was mainly related to the removal of potential host bacteria.The change of microbial community structure(λ=0.83,P<0.01)and MGEs(λ=0.60,P<0.05)were the main factors affecting the fate of ARGs.The addition of biochars were not directly affect the fate of ARGs(λ=0.29,P>0.05).The addition of biochar reduced the content of bioavailable metals,thus reducing selective pressure in the AD.And the addition of biochar altered the microbial population structure and reduced the abundance of MGEs and MRGs,thus indirectly promoting the removal of ARGs during AD.